• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.547-555
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• 2012

This paper focuses on the research of the anode and cathode in the Ni-MH secondary battery. In this paper, the proposed method employs a continuous wave Nd : YAG laser based on the pure Ni instead of the low carbon steel to improve the conductivity although the conventional secondary battery is based on the resistance spot welded with low carbon steel SS41. It welds a sandwich panel using the pure Ni and the porous thin plate, and the tested optimal conditions for the laser power and irradiation speed were 300 and 350 Watt, and 1.0~1.6m/min, respectively. Finally, we observed a ratio, heat input and cross-section and measured the conductivity of the welding section to test the weldability.

• Journal of Korean Society of Steel Construction
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• v.14 no.1
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• pp.41-49
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• 2002

An efficient algorithm automatically determining cross sectional properties of thin-walled beams is developed using the minimum information about geometry of the cross section. This scheme is applied to automatic calculation of normal and shear stress distribution corresponding to stress resultants as well as sectional constants for complex open and closed thin-walled sections. Numerical examples evaluating section constants and stress distributions is presented and compared with the available reference's results.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.3
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• pp.188-194
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• 2016

Accurate estimation of shear flows in thin-walled beam section is the key issue to evaluate shear stress distribution of ship hull transverse section under the shear forces acting on hull girder. It is regarded that the method using the warping functions obtained by finite element formulation is the state of the art of this field. Recently, however, IACS took effect the new version of CSR in which direct calculation process of shear flow was suggested. In the direct calculation process, shear flow of ship hull section can be obtained by the addition of determinate and indeterminate shear flows calculated respectively. So, in this paper, the shear flow evaluation codes based on the process proposed by IACS CSR and warping function based method were developed respectively. The calculated results of shear flows for the several examples of ship sections were compared with each other and considered in detail.

• Journal of Korean Society of Steel Construction
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• v.14 no.1
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• pp.31-40
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• 2002

Free vibration of a thin-walled laminated composite beam is studied. A general analytical model applicable to the dynamic behavior of a thin-walled channel section composite is developed. This model is based on the classical lamination theory, and accounts for the coupling of flexural and torsional modes for arbitrary laminate stacking sequence configuration. i.e. unsymmetric as well as symmetric, and various boundary conditions. A displacement-based one-dimensional finite element model is developed to predict natural frequencies and corresponding vibration modes for a thin-walled composite beam. Equations of motion are derived from the Hamilton's principle. Numerical results are obtained for thin-walled composite addressing the effects of fiber angle. modulus ratio. and boundary conditions on the vibration frequencies and mode shapes of the composites.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.1
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• pp.135-147
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• 2000

Section design of vehicle structure has been developed by two methods. One is the section property method which uses section property as a design variable. This method shows the tendency of an optimum section approximately. The other method is the section shape method which utilizes geometric parameter of section as a design variable. Practical solutions are obtained by this method. However, it is very expensive for large-scale problems due to the large number of geometric parameters. These two methods are compared through several sample problems. The finite element method is used for the structural and sensitivity analyses. The results are analyzed based on the number of function evaluations, the quality of cost function, the complexity of programing, and etc. The applications of both methods are also discussed.

• Steel and Composite Structures
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• v.45 no.2
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• pp.219-230
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• 2022

The aim of this paper is to study the mechanical behaviors of the cold-formed thin-walled steel and reinforced concrete sandwich composite slab (CTS&RC-SCS) under vertical loads and to develop the calculation methods of its flexural bearing capacity and section stiffness. Two CTS&RC-SCS specimens were designed and manufactured to carry out the static loading test, and meanwhile, the numerical simulation analyses based on finite element method were implemented. The comparison between experimental results and numerical analysis results shows that the CTS&RC-SCS has good flexural capacity and ductility, and the accuracy and rationality of the numerical simulation analysis are verified. Further, the variable parameter analysis results indicate that neither increasing the concrete strength grade nor increasing the thickness of C-sections can significantly improve the flexural capacity of CTS&RC-SCS. With the increase of the ratio of longitudinal bars and the thickness of the composite slab, the flexural capacity of CTS&RC-SCS will be significantly increased. On the basis of experimental research and numerical analysis above, the calculation formula of the flexural capacity of CTS&RC-SCS was deduced according to the plastic section design theory, and section stiffness calculation formula was proposed according to the theory of transformed section. In terms of the ultimate flexural capacity and mid-span deflection, the calculated values based on the formulas and the experimental values are in good agreement.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.3
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• pp.400-407
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• 1987

Thin film filter type 4-channel wavelength division multiplexing(WDM) device was designed and fabricated for the application in optical subscriber loop system. It has multi-mode fiber pigtails and four wavelength division consisting of 0.81, 0.89, 1.2 and 1.3 um. The evaluated performances are 1-2d B of insertion loss(connector loss excluded)and 30-35d B of crosstalk attenuation for all channels. The performance of the fabricated device was tested in the wideband optical transmission experiment, where the SNR degradation due to the crosstalk of the device was found to be within a measurement error.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.325-331
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• 2004

Generally, the buckling of thin-walled structures has studied for rectangular sections or circular sections. Rectangular sections have small stiffness and circular sections have large stiffness when they are compared with rectangular sections for local buckling. But both of them have similar stiffness to column buckling. Therefore in this paper, we are going to analyze the local buckling for the box section with rounded comer and compare with rectangular section. Also we confirm that the rounded comer section has larger local buckling strength than rectangular section.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.2
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• pp.57-68
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• 1998

For free vibration of monosymmetric thin-walled circular arches including restrained warping effect, the elastic strain and kinetic energy is derived by introducing displacement fields of circular arches in which all displacement parameters are defined at the centroid axis. The cubic Hermitian polynomials are utilized as shape functions for development of the curved thin-walled beam element having eight degrees of freedom. Analytical solution for free vibration behaviors of simply supported thin-walled curved beam element is presented by evaluating elastic stiffness and mass matrices. In order to illustrate the accuracy and practical usefulness of this study, analytical and numerical solutions for free vibration of circular arches are presented and compared with solutions analyzed by the FEM using straight beam element.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.167-171
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• 2005

The thick open section composite beams are used extensively as load carrying members and stiffeners of structural elements. However, most of studies on thick composite beams are limited only to closed section beams. In this study, an open cross-section thick-walled composite beam model which includes coupled stiffness, transverse shear, and warping effects is suggested and the deflections associated with the thick-walled composite beams and thin-walled composite beams are obtained and compared with the finite element analysis results. The correlation between thin and thick walled composite beam was achieved for two different layup configurations which are the circumferentially asymmetric stiffness (CAS) and circumferentially uniform stiffness (CUS) beams.